The main difference between a conductor and an insulator is that the conductor allows the flow of electric current through it. whereas an insulator does not allow the flow of current through it.
In electrical and electronics engineering, three types of engineering materials are used namely conductors, insulators, and semiconductors. In this article, we will discuss the conductor and insulator, along with the differences between them.
What is a Conductor?
A material that allows the flow of electric current through it is called a conductor. The metals are examples of conductors. The conductor materials also allow the conduction of heat.
In the conductors, the flow of the current of heat is mainly due to free electrons. When a voltage is applied across a conductor, it causes a directed flow of free electrons through the conductor, and hence the flow of current.
The conductors are materials that have the highest conductivity among the three materials (conductors, semiconductors, and insulators). However, different conductor materials have different degrees of conductivity depending on the availability of free electrons in the conductor, which means the conductivity of a conductor is directly proportional to the number of free electrons in it.
In the terms of electrons in the last orbit of the atom of material, we can also define a conductor as “if a material has less than 4 electrons in its outermost shell, then it is called a conductor.”
While considering the energy band diagram of conductors, we found that their valance band and conduction band are overlapping each other, which means there is no forbidden energy gap that exists.
Examples of conductors are metals such as silver, copper, aluminum, gold, graphite, platinum, etc.
The electrical conductivity of the silver according to IACS (International Annealed Copper Standard) is highest among all types of conducting materials. However, being costly, it is not used for making the wires.
What is an Insulator?
An engineering material that restricts the flow of electric current through it is called an insulator. Therefore, contrary to the conductor, the insulator does not allow the movement of electrons through it. As a result, the conductivity shown by an insulator is negligible.
The reason behind the negligible conductivity of the insulators is the unavailability of free electrons in the material. The insulators have more than 4 electrons in their outermost shell. In the energy band, the insulators have a valance band that is full of electrons and a conduction band that is empty, and these two bands are separated by a very large forbidden energy gap, of the order of 10 eV. This large forbidden energy gap restricts the movement of electrons from valance band to conduction and results in almost zero conductivity.
The common examples of insulators are wood, paper, air, mica, glass, porcelain, plastic, rubber, etc.
Difference between Conductor and Insulator
The following table shows the major differences between the conductor and insulator.
Comparison Chart
| Basis of Difference | Conductor | Insulator |
| Definition | A material that allows the flow of electric current through it is known as a conductor. | A material that restricts the flow of electric current through it is called an insulator. |
| Number of free electrons in the last orbit | Conductors have less than 4 electrons in the outermost shell. | Insulators have more the 4 electrons in the outermost shell. |
| Electron flow | The electrons can flow freely through a conductor. | The electrons cannot flow through an insulator. |
| Conductivity | Conductors have conductivity very high than insulators. | The conductivity of insulators is almost zero. |
| Resistivity | The resistivity of the conductor is very low. | The resistivity of insulators is comparatively very high. |
| Temperature coefficient | Conductors have a positive temperature coefficient, which means their resistance increases with an increase in temperature. | Insulators have a negative temperature coefficient, i.e. their resistance increases with an increase in temperature. |
| Conductivity of heat | Conductors have high thermal conductivity. | The thermal conductivity of insulators is relatively low. |
| Inside electric field | The electric field inside a conductor is zero, i.e. does not exist. | The electric field can exist inside an insulator. |
| Forbidden energy gap | There is no forbidden energy gap in a conductor, i.e. the valance band and covalent band overlap each other. | A large forbidden energy gap exists in an insulator, of the order of 10 eV. |
| Valance band | The valance band of conductors remains empty. | The valance band of insulators remains full of electrons. |
| Conduction band | In the case of conductors, the conduction band remains full of electrons. | The conduction band of insulators remains empty. |
| Examples | All the metals like copper, silver, aluminum, gold, etc. are examples of conductors. | The common examples of insulators are wood, paper, rubber, plastic, mica, glass, etc. |
| Applications | The main use of conductors in electrical and electronics is for making wires and cables for power transfer. | Insulators are used to provide electrical leakage in electrical equipment. Also, used for making insulators for transmission and distribution lines. |
Conclusion
Hence, in this article, we have discussed several differences between conductor and insulator. One of the major differences between a conductor and an insulator is that a conductor allows the flow of current, whereas the insulator does not allow it. Although, both conductors and insulators are the two majorly used materials in the field of electrical engineering.